August 14

FE Practice Exam 1 Part IV

Problem #31

What the standard units used when using the Reynolds Number?
A) ft/s2
B) centipoise
C) kg/s
D) None

Problem #32

What is the thermal efficiency for a Carnot engine that operates between 100F and 400K?
A) 75%
B) 77.5%
C) 7.8%
D) 22.3%

Problem #33

What is the natural frequency of a body that has a period of oscillation of 2.7 seconds?
A) 2.7 s
B) 0.75 s
C) 2.33 s
D) 4.65 s

Problem #34

What cycle is the most efficient?
A) Carnot
B) Brayton
C) Diesel
D) Otto

Problem #35

An iron sphere with a mass of 1.5 kg hangs from a 15 cm long spring. If the spring constant is 0.75 N/m what is the period of oscillation when the sphere is pulled down and released?
A) 3.2 s
B) 8.9 s
C) 4.4 s
D) 12.5 s

Problem #36

A plane intercepts the coordinate axis at (4,6,10). What are the Miller indices for this plane?
A) (2,3,5)
B) (15,10,6)
C) (-4,-6,-10)
D) (10,6,4)

Problem #37

A copper ball that is 1.5 m in diameter has a temperature of 100C. The environment is at 0C. If the emissivity of copper is 0.15 how much power is radiated by the copper ball?
A) 6 w
B) 5,264 W
C) 500 W
D) 1,164 W

Problem #38

What would the annuity be over a 20 year period that has an interest rate of 10% and a present worth of $500? A)$58.75
B) $42.55 C)$8.51
D) \$ 63.75

Problem #39

A group of dog pulls a sled across a snow covered surface. It takes 5 hours to pull the 200 kg sled 100 kilometers. If the static friction is 0.4 and the dynamic friction is 0.1 what is the average power exerted by the dog sled team?
A) 1,067 W
B) 5,333 W
C) 3,84 kW
D) 266.8 W

Problem #40

Reactions on average will proceed faster at a higher temperature because of which of the following?
A) There is less energy in the molecules
B) Molecules collide more frequently
C) The amount of exergy is diminished
D) The energy to start the reaction is higher

August 13

FE Practice Exam 1 Part IV Answers

Solution #31

The Reynolds number is a dimensionless number

Choice D is correct

Solution #32

$\eta = 1 - \frac{T_c}{T_h}$

$T_c = ((100^{\circ} F) - 32)(\frac {5}{9}) + 273 = 311\ K$

$\eta = 1 - \frac {311}{400} = 0.2225$

Thermal efficiency = 22.25%

Choice D is correct

Solution #33

$w = \frac {2\pi}{T}$

$w = \frac {2\pi}{2.7\ s} = 2.33 s$

Choice C is correct

Solution #34

The Carnot cycle is the most efficient since it is completely reversible

Choice A is correct

Solution #35

$T = 2 \pi \sqrt {\frac {m}{k}}$

$T = 2 \pi \sqrt {\frac{1.5}{0.75}} = 8.9 s$

Choice B is correct

Solution #36

To find the Miller indices you must take the reciprocal of each intercept. Then convert to whole numbers

Original Coordinates $(4,6,10)$

Reciprocal Coordinates $(\frac {1}{4}, \frac {1}{6}, \frac {1}{10})$

Convert to whole numbers by multiplying by 60 to remove the denominator$(15,10,6)$

Choice B is correct

Solution #37

$E = \epsilon \sigma T^4A$

Area for a sphere

$A_S = 4\pi (\frac {d}{2})^2$

$A_s = 4\pi (\frac{1.5}{2})^2 = 7.07 m^2$

$E = (0.15)(5.67x10^{-8} \frac{W}{m^2K^4})(273 + 100C)^4(7.07m^4) = 1164\ W$

Choice D is correct

Solution #38

$A = P(A/P,i,n)$

$A = (500)(A/P,10\%,20)$

$A = (500)(0.1175) = 58.75$

Choice A is correct

Solution #39

$F_f = \mu N$

$F_f = (0.1)(9.81\ \frac {m}{s^2})(200\ kg) = 196.2\ \frac{kg\ m}{s} = 196.2\ N$

$W = Fd$

$W = (196.2\ N)(100\ km)(\frac {1000m}{1 km}) = 19,200,000\ J$

$P = \frac {W}{t}$

$P = (\frac {19,200,000 J}{5 hours})(\frac{1 hour}{3600 s}) = 1067 W$

Choice A is correct

Solution #40

The molecules are traveling faster with a higher temperature which increasesthe chance of collision.

Choice B is correct

August 11

FE Practice Exam 1 Part III Answers

Solution #21

The substance is losing electrons

B is the correct choice

Solution #22

The cable needs to be changed into a point load with the mass at the midpoint of 150 meter.

$W = \Delta PE + \Delta KE$

$PE = mgh$

$W_{cable} = (\frac {5 kg}{1\ m})(300\ m)(9.81 \frac {m}{s^2})(150\ m) = 2,207,250\ N$

$W_{shipping\ container} = (500\ kg)(9.81 \frac {m}{s^2})(300\ m) = 1,471,500\ N$

$W_{total} = 1,471,500 + 2,207,250 = 3,678,750\ N$

Choice D is the closest with 3,680 kN

Solution #23

The Carnot cycles is defined by two isentropic and two isothermal processes.

Choice C is correct

Solution #24

$(9+3i)(6+8i) = 54 + 72i + 18i + 24i^2$

$54 + 90i - 24 = 30 + 90i$

Choice A is correct

Solution #25

Find the molecular weights of each compound
CH4      16
CO2      44
O2        32
N2        28

Find the total mass

$16(0.22) + 44(0.45) + 32(0.05) + 28(0.14) = 28.84$

Percentage of CH4

$\% = \frac {16(0.22)}{28.84}\ =\ 12.21\%$

Choice C is correct

Solution #26

$\sigma = \frac {F}{A}$

$65,000\ \frac {lbs}{in^2} = \frac {F}{(12\ in)(6\ in)}$

$F = 4,680,000\ lbs$

Choice B is correct

Solution #27

From the steam tables

$v_f = 0.001043\ \frac {m^3}{kg}$

$u_f = 417.3\ \frac {kJ}{kg}$

$v_g = 1.694\ \frac {m^3}{kg}$

$u_g = 2505\ \frac {kJ}{kg}$

$m_g = \frac{40 m^3}{1.694 m^3/kg} = 23.6\ kg$

$m_f = \frac {10 m^3}{0.001043 m^3/kg} = 9,587\ kg$

$u = (u_f)(m_f) + (u_g)(M_g)$

$u = (417.3 \frac {KJ}{kg})(9,587 kg) + (2505 \frac {kJ}{kg})(23.6 kg) = 4,060,000\ kJ$

Choice A is correct

Solution #28

$area = \frac {\pi D^2}{4}$

$area = \frac {\pi (10\ in)^2}{4} = 78,54\ in^2$

$p = \frac {lbf}{a}$

$p = \frac {300 lbf}{78.54 in^2} = 2.56\ psi$

Convert to metric

$Pa = (\frac {2.56 lbf}{in^2})(\frac {4.448 N}{1 lbf})(\frac {1 in}{2.54 cm})^2(\frac {100 cm}{1 m})^2 = 17,651\ Pa$

$17,651 Pa = 17.7 kPa$

Choice A is correct

Solution #29

First the units need to be consistent

$\dot m = (120 \frac {lbm}{min})(\frac {1\ min}{60\ seconds}) = 2\ \frac {lbm}{s}$

$h_2 = (10 \frac{btu}{oz})(\frac {16\ oz}{lbm}) = 160\ \frac{btu}{lbm}$

$Q = \dot m (h_2 - h_1) = (2 \frac {lbm}{s})(160 - 50)\frac{btu}{lbm} = 220\ \frac {btu}{s}$

$Q = (220 \frac {btu}{s})(1.055 \frac {kJ}{btu}) = 232.1 \frac {kJ}{s} = 232.1\ kW$

Choice B is correct

Solution #30

The cylinder can either continue rolling or fall over to one side so there are two degrees of freedom

Choice B is correct

August 11

FE Practice Exam 1 Part III

Problem #21

What is happening to a substance when it is oxidized?
A) The substance is gaining electrons
B) The substance is losing electrons
C) The substance is giving off heat
D) The substance is absorbing heat

Problem #22

A 500 kilogram shipping container is raised from 300 meters. If the cable weight 5 kilograms per meter of length, what is the approximate work done?
A) 5,886 kN
B) 2,210 kN
C) 1,472 kN
D) 3,680 kN

Problem #23

What are the basic processes for an ideal, reversible Carnot cycle
A) Four isentropic
B) One isentropic, isobaric, isochoric, and isenthalpic
C) Two isothermal and two isentropic
D) Two adiabatic and two isobaric

Problem #24

Simplify the following expression

$(9+3i)(6+8i)$

A) 30 + 90i
B) 78 + 90i
C) 24i2 + 90i + 54
D) 54 + 90i

Problem #25

What is the percentage of CH4 on a mass basis if the volumetric analysis of the mixture is as follows

CH4     22%
CO2     45%
O2          5%
N2       14%

A) 68.7%
B) 5.6%
C) 12.2%
D) 13.6%

Problem #26

What is the largest load a 12 inch by 6 inch column can support if the normal stress can not exceed 65,000 PSI?
A) 130,000 lbs
B) 4,680,000 lbs
C) 32,500 lbs
D) 2,340,000 lbs

Problem #27

A 50 m3 vessel contains a mixture of 80% water and 10 m3 of water vapor. If the internal pressure of the vessel reads 100 kPa, what is the internal energy of the system?
A) 4,060,000 kJ
B) 4,000,000 kJ
C) 60,000 kJ
D) 3,940,000 kJ

Problem #28

A flange weighing 200 lbs is resting on a table. If the diameter of the flange is 10 inches what pressure does the flange exert on the table?
A) 17.7 kPa
B) 17.7 Pa
C) 2.56 kPa
D) 2.56 Pa

Problem #29

How many kilowatts are required to heat a flowing liquid that has a mass flow rate of 120 lbm/min with an entering enthalpy of 50 BTU/lbm and a leaving enthalpy of 10 BTU/oz?
A) 101.3 kW
B) 232.1 kW
C) 6,077 kW
D) 13,930 kW

Problem #30

You observe a 12 inch diameter by 0.5 in thick cylinder rolling along a horizontal surface. How many degrees of freedom does the cylinder have?
A) One
B) Two
C) Three
D) Four

August 8

FE Practice Exam 1 Part II

Problem #11

Which of the following statements is FALSE when concerning the hot working of metal?
A) Produce a fine grained product
B) Removes strain hardening
C) Combines of annealing and cold working
D) Decreases the density of the metal

Problem #12

What is the elongation of a 2 meter aluminum bar when it has been stressed to 512 MPa? (E = 69 GPa)?
A) 1.5 cm
B) 2.0 cm
C) 1.0 cm
D) 1.7 cm

Problem #13

Which of the following is FALSE with regards to creep
I. May involve the sliding of whole grains
II At high stresses creep is controlled by the movement of vacancies.
III Also known as hot flow
IV Creep is a time dependent deformation
A) I
B) II
C) III
D) IV

Problem #14

What is the oxidation state of Carbon in Carbonate (CO3-2)
A) -2
B) 4
C) 1
D) 2

Problem #15

A piston inside a cylinder undergoes an isentropic compression with the following values.
$p_1= 4.57 \frac{N}{cm^2}$

$p_2= 34.07 \frac{N}{cm^2}$

$V_1 = 257 cm^3$
If the specific heat ratio (k) is 1.4, What is the compressed volume?
A) 61.2  cm3
B)  30.5 cm3
C)  90.4 cm3
D)  257 cm3

Problem #16

What is the standard equation for calculating the future worth (F) when given the annual rate of return (I) and the present rate (P)?
A) $F=P(1+i)^{n-1}$
B) $F=P(1+i)^n$
C) $F=P(1-i)^n$
D) $F=P(1+n)^I$

Problem #17

A tube that is 10 feet long and 2 feet in diameter is placed in an air stream. The flow of the air is at a speed of 15 ft/s and is perpendicular to the long axis of the tube. If the coefficient of drag is 1.3 and the density of air is 0.075 lbm/ft3 What is the drag on the cylinder?
A) 150 lbf
B) 200 lbf
C) 320 lbf
D) 220 lbf

Problem #18

If a process is considered to be internally reversible and adiabatic, what can the change in entropy be assumed to be?
A) Entropy becomes Infinite
B) Entropy increases
C) Entropy decreases
D) Entropy does not change

Problem #19

What is the hydraulic diameter of a 20 inch diameter pipe that is half full?
A) 10 inches
B) 2.5 inches
C) 20 inches
D) 5 inches

Problem #20

You are tasked with identifying where the stress concentrations may appear on a support beam. Of the following locations which will not have a stress concentration?